Choose a fraction that you will represent on the number line. As an example, start with the fraction "1/2."
Create a number line that is subdivided into parts that equal the number in the denominator of the number line. For the example "1/2," divide the number line into two parts.
Label the number line starting with 0 and incrementing to the number in the denominator of the fraction for positive fractions. As an example, for the fraction "1/2," the subdivisions of the number line would be 0,1/2 and 2/2.
Teach the students how they can move up the number line by adding to a fraction and move down the number line by subtracting from the fraction.
Use variations of the same fraction to teach the concept of parts. Divide another number line into 6 parts and label the midway point "3/6." Explain how "3/6" is the same as "1/2" by comparing the two number lines.